<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>let 命令</title>
 <script>
 const obj = {};
 // 为 obj 对象添加一个属性，是可以的
 obj.age = 23;
 console.log(obj.age); // 23
 // 尝试修改 obj 的引用地址，就会报错
 // Uncaught TypeError: Assignment to constant variable.
 obj = {};
 </script>
 </head>
 <body></body>
 </html>